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Metal vapor discharge lamp

a technology of metal vapor and discharge lamp, which is applied in the direction of discharge lamp, low-pressure discharge lamp, discharge tube luminescnet screen, etc., can solve the problems of metal vapor discharge, nitrogen gas pressure inside the outer tube will decrease, and the temperature in the arc tube will not be adjusted properly, so as to reduce the effect of metal vapor pressure increase, reducing the effect of metal vapor pressure, and reducing the effect of life properties

Inactive Publication Date: 2005-03-01
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention is a metal vapor discharge lamp that offers improved performance by restraining the increase in metal vapor pressure inside the arc tube during use. This is achieved by avoiding chemical reactions between the metal members and nitrogen gas, which leads to the formation of ammonia and the subsequent reaction with iron to generate iron nitride. The metal members are designed to be chemically stable at high temperatures, and the outer tube is enclosed with a nitrogen gas to maintain the nitrogen gas pressure and prevent electrical breakdown. The structure of the metal members in the outer tube includes wiring for supplying power to the arc tube, and the metal material used in the outer tube should not react with nitrogen or nitrogen compounds. The use of a specific metal material, such as stainless steel or molybdenum, can also be employed to further enhance the stability of the lamp."

Problems solved by technology

Meanwhile, the inventors of the present invention have observed that a conventional metal vapor discharge lamp has a problem in that a nitrogen gas pressure inside the outer tube will decrease as the lamp is used over a long period of time.
Accordingly, the temperature in the arc tube will not be adjusted properly during the lamp illumination.
As a result, it becomes very likely to cause a problem of changing the life property which is attributable to the increase in the vapor pressure of the arc tube.
Accordingly, at such times as applying a high pressure pulse to the lamp, and non-illumination time attributable to leakage from the arc tube at the end of life of the lamp, it becomes possible that an arc discharge or a glow discharge is generated between the wires inside the outer tube (i.e. between opposite polarity electrodes), thereby causing an electrical breakdown.
This seriously damages the illuminating performance of lamps, and is considered a problem to be solved immediately.

Method used

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Examples

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embodiment 1

(Embodiment 1)

1—1. Structure of Metal Vapor Discharge Lamp

FIG. 1 is a front sectional view showing a part of the metal vapor discharge lamp, in structure, with an output of 250 W, which relates to the embodiment 1.

As shown in FIG. 1, the present metal vapor discharge lamp has a structure in which, inside a cylindrical outer tube 8 having a round bottom, a stem 6 made of heat-resistance glass is connected to an arc tube 1, via stem lines 5a, 5b, and the power supply lines 4a, 4b, that are wiring members, the arc tube 1 including therein a main tube 10, and thin tubes 11a and 11b, that are made of alumina ceramic. The sizes of the lamp are, for example, a length of 220 mm, and a diameter of 50 mm. Needless to say, however, the present invention is not limited to such sizes, or to the form of the outer tube.

In the outer tube 8, a nitrogen gas is enclosed at about 350 Torr. The opening of the outer tube 8 is sealed by a frit glass filled in a base 9 and between the base 9 and the outer ...

embodiment examples

2. Embodiment Examples and Quality Experiments

As an embodiment example, a metal vapor discharge lamp of the stated embodiment 1 was produced. At the same time, as a comparison example, a metal vapor discharge lamp was also produced whose metal members that were exposed to a nitrogen gas inside the outer tube 8 are all made of nickel-plated iron material (i.e. concretely, the metal members being the sleeve supporting plates 3a, 3b, the power supply lines 4a, 4b, the stem lines 5a, 5b, and an outer portion of the getter 7). In the outer tube of each lamp, a nitrogen gas of 350 Torr was enclosed when the temperature was cold (about 25° C.). Ten lamps were produced for each of the embodiment example and the comparison example, and life experiments were conducted to see chronological changes in properties.

FIG. 3 and FIG. 4 are graphs summarizing the stated experiments.

Among the graphs, FIG. 3 is a graph showing changes in color temperature during the lives of the embodiment example and t...

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Abstract

A metal vapor discharge lamp has an arc tube in which mercury, a rare gas, and at least one luminous metal are enclosed, and an outer tube in which a nitrogen gas is enclosed and which covers the arc tube. The metal members which are provided in the outer tube and which include wiring for supplying power to the arc tube will not react with one of nitrogen and a nitrogen compound in the nitrogen gas atmosphere in the outer tube when the temperature exceeds 350° C. in a steady-state illumination. The use of a metal member such as stainless steel will increase the life of the discharge lamp.

Description

BACKGROUND OF THE INVENTION(1) Field of the InventionThe present invention relates to a metal vapor discharge lamp such as a metal halide lamp, and in particular, relates to a metal vapor discharge lamp having a nitrogen gas in its outer tube.(2) Related ArtA general structure of a metal vapor discharge lamp is such that an arc tube having mercury, a rare gas, and a luminous metal, is placed in an outer tube already having a nitrogen gas therein, and that electrodes of the arc tube and a base of the outer tube are electrically connected by wiring members. A nitrogen gas is used as an inert filling gas, and also plays a role of maintaining the temperature of the arc tube to an adequate level during the lamp illumination. The wiring members are composed of a power supply line, a stem line, and the like, that are placed inside the outer tube. The wiring members are used to support the arc tube from inside the outer tube, and also used to hold a sleeve surrounding the arc tube, when nec...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): H01J61/02H01J1/62H01J1/00H01J17/20H01J17/02H01J61/34H01J61/36H01J61/72
CPCH01J61/34H01J61/72H01J61/36
Inventor KAKISAKA, SHUNSUKETAKEDA, KAZUO
Owner PANASONIC CORP